Crt electrode claw structure embedded in mounting beads

ABSTRACT

An electron gun assembly has a flat centering plat which engages the inner surface of a CRT tube envelope by means of at least three projections extending from the plate, one of which is a spring member, to thereby hold the gun axis in a predetermined alignment position with close tolerances and to permit the gun to slip into and firmly engage the envelope inner surface. The gun has electrodes mounted between a pair of glass beads into which specially shaped edges of the gun electrodes are embedded. Thus, the flat plate has claw structure for engaging the beads which is formed by two U-shaped indentations generally converging toward the center of the plate to thereby permit a thin glass bead to engage and hold the gun elements firmly without fracture.

United States Patent Inventor Horst H. Blumenberg Owensboro, Ky.

Appl. No. 6,399

Filed Jan. 28, 1970 Patented Nov. 23, 1971 Assignee Kentucky Electronics, Inc.

Owensboro, Ky.

CRT ELECTRODE CLAW STRUCTURE EMBEDDED IN MOUNTING BEADS 5 Claims, 3 Drawing Figs.

US. Cl 313/256, 313/269. 313/292 Int. Cl ..H01j 19/52, H0l j 1/98 Field 0! Search 313/82, 269, 81, 284, 285, 289, 262, 256, 292

References Cited UNITED STATES PATENTS 2,701,320 2/1955 Kovach 313/82 2,778,966 1/1957 Faustimetal. 3,512,031 5/1970 Oberg Primary Examiner-Roy Lake Assistant ExaminerV. Lafranchi Attorney-Laurence R. Brown ABSTRACT: An electron gun assembly has a flat centering plat which engages the inner surface of a CRT tube envelope by means of at least three projections extending from the plate, one of which is a spring member, to thereby hold the gun axis in a predetermined alignment position with close tolerances and to permit the gun to slip into and firmly engage the envelope inner surface. The gun has electrodes mounted between a pair of glass beads into which specially shaped edges of the gun electrodes are embedded. Thus, the flat plate has claw structure for engaging the beads which is formed by two U-shaped indentations generally converging toward the center of the plate to thereby permit a thin glass bead to engage and hold the gun elements firmly without fracture,

PATENTED 23 I97! 3.622.831

INVENTOR HORST H. BLUMENBERG BY $4M gym ATTORNEY CRT ELECTRODE CLAW STRUCTURE EMBEDDED IN MOUNTING BEADS This invention relates to cathode-ray tubes and more particularly it relates to centering structure built into an electron gun assembly for holding the electron gun in a predetermined position within a tube envelope.

Snubber springs and electron gun centering structure for CR tubes has been known in the prior art. However, such prior art structure has not been dependable in holding the electron gun axis in a precisely known position to produce a beam centered by physical orientation rather than by electronically adjusted potentials. Particularly with the advent of miniaturized indicia display tubes it is necessary to hold the electron gun axis precisely centered within the tube envelope physically without the use of electronic centering means which may be economically employed in oscillograph or picture tube applications but which are not feasible in the case of every tube of a multidigit-display system.

Accordingly it is an object of this invention to provide improved centering means for holding electron guns in position within cathode ray tube envelopes.

Therefore in accordance with the invention a centering device comprises a flat plate member with at least three projecting edges which engage the inner surface of the tube envelope, one of which is a deformable spring member.

Further objectives, features and advantages of the invention will be found throughout the following more detailed description of the invention and the particular embodiments thereof shown in the accompanying drawing, wherein:

FIG. 1 is a partial top section view of an electron gun centering plate mounted within a CR tube envelope, as taken, for example, along lines 1-4 of FIG. 3;

FIG. 2 is a partial side view of the centering plate structure shown in FIGS. 1 and 3; and

H6. 3 is a foreshortened elevation view, partly broken away and partly in section, of a CR tube assembly constructed in accordance with the invention.

As may be seen in the drawing, the centering plate assembly comprises a flat plate with a centered aperture 1] about which are at least three projections l2, l3, l4 engaging the inner walls of a CR tube envelope 16 to hold the axis of an electron gun assembly 17 precisely centered inside the cylindrical tube envelope.

The various electrodes such as grid 20, anode 2], focus electrode 22 and deflecting plate 23 of the electron gun are held between two glass beads 24, 25 which electrodes have claw members 26 at the edge of the various electrodes embedded therein the hold each electrode in an exactly aligned position so that the electron beam axis will be centered in the cylindrical envelope 16 to strike very near the exact center of the screen on faceplate 27 by means of the physical location of the electrodes within the tube.

When conventional snubber springs or gun centering assemblies are used it is almost impossible to center the electron gun assembly within very close tolerances because of variations in spring pressure upon several fingers engaging the tube inner wall 15 at different locations. In the shown structure, however, the projections 12 and 13 absolutely identify the position of the gun by registration with and against the inner cylindrical tube walls 15, and the spring member [4 permits the frictional entry and positioning of the gun within the cylindrical tube 16 to attain the desired position.

The spring member 14 could be integral and bent downwardly from a plate member 10, but is preferably a separate member of proper elastic properties which can be readily assembled by means of a hole 30 and notch 31 in the centering plate 10 in the manner shown by FIG. 2. If desired the bowed section 32 can be flattened and spot welded to the plate 10 to have the spring assembly l4 mechanically secured to plate 10.

As shown in FIG. 1, the claw members 35 of the electrode plate member such as 10 are specially constructed to enter and embed in bead 25 without fracture during assembly or when forcing the gun into the cylindrical envelope 16. Thus two U-shaped indentations 36, 37 have their bottom portions generally converging in a direction toward the centered beam axis 38 as indicated by center lines 39, 40.

The generally rectangular cross section of bead 25 is permitted to span the gap between the two indentations 36, 37 of claw structure 35 along the major axis to engage the plate 10 at extremities 42. Outwardly converging or tapered sides 43 permit the claw member 35 to enter a molten bead and engage it firmly without causing a fracture as might a conventionally shaped claw when the centering plate is subject to considerable physical pressure when forced into the tube envelope. The bead 25 has a minor dimension about the same as the depth of the indentations 36, 37, and the bead is symmetrically placed on the claw portions 35 without penetrating the depth of the minor dimension to allow gaps 44 to remain in the bottom of notches 36, 37. This structure helps to permit a miniaturized tube of less than one inch in diameter to be manufactured with precise dimensions and tolerances using small glass beads and special centering structure to help establish and maintain dimensional stability and electron beam axis alignment by physical positioning of the gun structure within the envelope 16.

Two centering plates 10 and 10' may be mounted at spaced positions along the electron gun assembly 17 normally disposed with the tube or electron beam axis to have therebetween a plurality of electrodes as shown in FIG. 3. Preferably each centering plate serves only as a centering plate in the gun assembly and not as a gun electrode. This is particularly important for grid 20 which is critically spaced and oriented. Thus when the gun assembly 17 is forced within envelope 16, before stem 45 is affixed, any tendency to warp or twist the centering plate 10 will not affect the alignment or performance of the electron beam. The electron gun 17 with centering structure at both ends thereof thus holds the axis of the electron beam closely along the envelope axis to attain a centered beam by physical orientation of the gun within precise limits that can be maintained from tube-to-tube.

Accordingly the structure herein disclosed has advanced the state of the art and permitted the manufacture of miniaturized CR tubes with very closely defined tolerances and precisely centered electron beams, and therefore has patentable merit.

What is claimed is:

1. An electron gun mounted in a cathode-ray tube envelope, said electron gun having a pair of glass beads for mounting electrodes thereon and electrodes embedded into said pair of glass beads comprising in combination, a substantially flat plate with an aperture disposed therethrough for passing an electron beam, said plate having at least one spring member extending therefrom and being shaped with a plurality of projections defined thereon to engage the inner surface of a cathode ray tube envelope at at least three spaced positions and having two straight edges with at least two spaced indentations therein defining three claw portions extending from said plate into said beads to an extend not reaching the bottom of the indentations one said projection comprising said spring member, with said plate and said projections proportioned to hold said plate and any electron gun assembly attached thereto in a predetermined position within said envelope defining the path of said electron beam inside said tube within close limits.

2. An electron gun as defined in claim 1 wherein the claw portions comprise a metallic portion defined by said plate with two generally U-shaped indentations having the bottom portions converging in a direction generally oriented toward the center of said plate.

3. Centering means as defined in claim 1 with said claw portions disposed on two substantially parallel edges of said plate and with each claw embedded in a corresponding one of said pair of spaced glass beads to hold said plate in a position substantially normal to the axis of said envelope.

4. An electron gun assembly with a spaced pair of glass beads comprising at least one flat plate member with an aperture therein to pass therethrough an electron beam, said plate member having one claw portion-embedded in each of said glass beads with the claw portions formed in an edge of said plate by two generally U-shaped indentations spaced on opposite sides thereof with the bottom portions of said indentations converging together in a direction generally oriented toward the center of said plate wherein said beads are generally rectangular in cross section shape and their major dimension is slightly greater than the span between said two U-shaped indentations in the edge of said plate thereby engaging said plate in positions on opposite sides of both said indentations, and the minor dimension of said beads is approximately that depth of the U-shaped indentations and said claw portions engage said beads substantially symmetrically without penetrating through the minor dimension.

5. An assembly as defined by claim 1 wherein the U-shaped indentations have straight sides oriented parallel to the axis of convergence.

I l 0 I 

1. An electron gun mounted in a cathode ray tube envelope, said electron gun having a pair of glass beads for mounting electrodes thereon and electrodes embedded into said pair of glass beads comprising in combinatiOn, a substantially flat plate with an aperture disposed therethrough for passing an electron beam, said plate having at least one spring member extending therefrom and being shaped with a plurality of projections defined thereon to engage the inner surface of a cathode ray tube envelope at at least three spaced positions and having two straightedges with at least two spaced indentations therein defining three claw portions extending from said plate into said beads to an extent not reaching the bottom of the indentations, one said projection comprising said spring member, with said plate and said projections proportioned to hold said plate and any electron gun assembly attached thereto in a predetermined position within said envelope defining the path of said electron beam inside said tube within close limits.
 2. An electron gun as defined in claim 1 wherein the claw portions comprise a metallic portion defined by said plate with two generally U-shaped indentations having the bottom portions converging in a direction generally oriented toward the center of said plate.
 3. Centering means as defined in claim 1 with said claw portions disposed on two substantially parallel edges of said plate and with each claw embedded in a corresponding one of said pair of spaced glass beads to hold said plate in a position substantially normal to the axis of said envelope.
 4. An electron gun assembly with a spaced pair of glass beads comprising at least one flat plate member with an aperture therein to pass therethrough an electron beam, said plate member having one claw portion embedded in each of said glass beads with the claw portions formed in an edge of said plate by two generally U-shaped indentations spaced on opposite sides thereof with the bottom portions of said indentations converging together in a direction generally oriented toward the center of said plate wherein said beads are generally rectangular in cross section shape and their major dimension is slightly greater than the span between said two U-shaped indentations in the edge of said plate thereby engaging said plate in positions on opposite sides of both said indentations, and the minor dimension of said beads is approximately that depth of the U-shaped indentations and said claw portions engage said beads substantially symmetrically without penetrating through the minor dimension.
 5. An assembly as defined by claim 1 wherein the U-shaped indentations have straight sides oriented parallel to the axis of convergence. 